Surgical clamp for fixation of bone fragments

ABSTRACT

The present invention relates to an implantable clamp for fixation of one or more bone fragments (82, 85) to a stable bone (81). The clamp has two basic functions, namely a buttress function and a clamp function. Either function or both may be employed depending on the fracture picture. The clamp has a first part (71) having a front part bent into a buttress (79) and/or into a lower part (77) of a clamp. Further, the clamp may comprise a second part (72) constituting the upper part (73) of the clamp. A screw (74) is used to secure the clamp to the stable bone (81). The buttress (79) of the clamp is utilized to press an intra-articular fragment (85) against an adjacent joint surface. The clamp (73, 77) is utilized to capture and secure a bone fragment (82).

FIELD OF THE INVENTION

The present invention relates to an implantable means and especially toa surgical clamp for fixation of bone fragments.

BACKGROUND AND PRIOR ART

A fracture near a joint has always been difficult to treat as the idealtreatment is to achieve rigid fixation of the fracture fragments whileallowing nearly immediate motion of the joint.

In order to simplify the description the present invention is describedin connection with fractures about the wrist, and particularly thosefractures collectively referred to as Colles' fractures. A personskilled in the art will appreciate that the invention is also applicablein fixation of other bones. Possible other bones include, but are notlimited to, bones of the elbow, knee, and ankle. This may require achange of the shape of the device for each specific area, but the sameprinciples are used irrespective of the site of the fracture. However,the major use of the invention is thought to be for fixation of Colles'fractures.

Treatment of distal radius fractures has been a problem, both because ofthe frequency of the injury as well as the difficulty in treating them.The goal of treatment is to restore joint congruity and anatomy,minimize the risk of arthritis, and maximize joint mobility. However,although these injuries are almost always treated on an outpatientbasis, they typically result in stiffness, arthritis, and diminishedfunction.

There are today essentially four general groups of options available forthe treatment of Colles' fractures: (1) closed reduction and casting,(2) external fixation, (3) open reduction and internal fixation, and (4)percutaneous pinning and/or limited open pinning. Each method has itslimitations; each has its benefits.

Closed reduction simply involves setting or aligning the broken bonemanually and applying a cast to the arm. This treatment avoids anytrauma associated with surgery, and is relatively inexpensive. However,it has several disadvantages. It involves cast immobilization untilhealing of the bone fragments occurs; this frequently results inconsiderable stiffness. This stiffness is not just confined to the wristand forearm. Immobilizing the arm in an elderly individual often resultsin considerable stiffness to the fingers, elbow, and shoulder as well.In addition, this technique is very limited in its ability to hold allbut the simplest, most stable fracture patterns in proper alignment.Unstable fractures commonly redisplace during healing, which can lead toarthritis and pain.

External fixation involves the application of relatively large diameterpins inserted into the finger metacarpal bones of the fingers and intothe radius above the fracture. These pin clusters are then connectedwith a bar or frame, essentially "bypassing" the fracture site.Typically, two pins are placed in the hand, and two pins in the radius.The frame may distract the wrist as well, in order to assist withfracture reduction, by using the soft tissue sleeve around the fractureto help squeeze the fragments into position. Although external fixationhas its proponents, it has its problems. The wrist and hand are rigidlyheld by the frame, and the pins through the skin tend to irritate thetendons and cause scarring. These problems together cause considerablestiffness in both the wrist and the fingers. Frequently the functionalloss of grip can be more disabling than the fracture. Pin siteinfections may also occur and compromise results. External fixation maynot achieve an anatomic reduction of the fragments. Currently, externalfixation is used for more severely comminuted, fragmented fractures.

Open reduction involves making an incision over the wrist reducing thefragments, and applying plates, screws, and pins as needed. For theColles' fracture open reduction and internal fixation is seldom used,for several reasons. First, the trauma associated with the dissectionand exposure can lead to scarring of the tendons, loss of gliding, andstiffness. Second, the dissection can compromise the blood supply to thefragments, which can result in delayed unions and occasionallynon-unions. Third, the fragments tend to be small and osteoporotic;drilling holes and placing screws frequently fragments these piecesfurther, making anatomic reduction even more difficult. Fourth, most ofthe fragments and displacement in the typical Colles' fracture are onthe dorsal side, and the irregularity of the radius in this areatogether with the many tendons found near the bone on this side makes itundesirable to place plates and screws dorsally. Finally, thesefractures are often comprised of numerous small pieces which must bereduced in a jigsaw puzzle type of arrangement, not easily treated byplate and screw fixation.

Percutaneous pinning involves the placement of small stiff pins, alsocalled K-wires, across fragments of the fracture. The pins may beinserted directly through the skin while imaging the fracture with afluoroscopy unit. Limited small incisions may also be used. Typically,pin diameters range from 0.010" to 0.250", with the 0.045" and 0.054"pin sizes commonly used in the USA. Pinning has certain advantages.Using a percutaneous or limited open technique to pin fragments allowsthe fracture to be internally fixed. This provides some additionalstability internally which is not available when the fracture is treatedwith a cast alone. The fragments in these fractures tend to be small andthe bone osteoporotic. As a result, pins are more appropriate as a typeof fixation than screws in this setting. A small diameter pin has lesschance of weakening the fragment and comminuting it further comparedwith screw holes that are made with even small diameter bone screws.

Pinning, however, has its problems. In order to secure a fragment, theremust be a stable bone nearby for securing the pin. Frequently, the onlystable piece of bone is the proximal fragment, which may be somedistance and at a difficult angle away from the fragment to be pinned.Since the pins have a small diameter, they are likely to bend ordisplace if the stable piece of bone is relatively far from the fracturefragment. This reduces the ability of the pin to maintain the positionof the fragment and, in turn, impedes the process of healing.

In certain cases multiple fragments are put together like stackingcards, by fixing one fragment to a stable proximal piece, and thenpinning a second fragment to the first, which is assumed to bestabilized by the first pin. This frequently makes the entire assemblydependent upon one or two pins which may engage the stable proximalcortex at some distance from the fracture fragment. Such situations areoften unstable.

Because pins have a strong tendency to bend and displace due to motionof the joint, pins are hardly ever used without casting. This means thatthe patient is still subjected to the common complications of stiffnessand loss of function that is associated with the cast.

The applicant's patent application SE 9500285-3 describes a method forusing pins together with a pin plate for fixation and stabilization ofthe pin or pins penetrating the bone fragments. This method overcomesmany of the problems involved with previous methods of treating manytypes of Colles' fractures when using pins. It achieves the objective ofproviding rigid fixation of the fracture fragments while allowingimmediate mobility of the joint.

However, pinning the fracture is not suitable or even possible for alltypes of Colles' fractures. Often, in order to use pins, there needs tobe a stable piece of bone for attaching the pin located on the oppositecortex of the fragment from where the pin is inserted. If the onlynearby solid piece of bone is located on the cortex adjacent to thefracture fragment, pinning becomes a geometric impossibility. An exampleof such a situation occurs when a Colles' fracture results in a dorsalulnar fragment and a fracture of the opposite volar radial surface. Inthese cases, there is no stable cortex available for angles of pininsertion which are technically feasible.

In some cases, the hole itself created by placing a pin or screw tosecure a small fragment would significantly weaken the fragment andcompromise fixation and stability. In such situations, these devices mayfurther comminute the fracture.

In other situations, fractures of the distal radius result in multiplepieces, creating dorsal, palmar, and intra-articular fragments. In suchcases, it is difficult to support the various fragments in theappropriate anatomic position simply by pinning. Moreover, fragmentswhich are completely intra-articular are not well treated with simplepinning, since leaving a pin through an articular surface can destroythe adjacent articular surface, resulting in severe arthritis.

SUMMARY OF THE INVENTION

An object of the invention is to provide implantable means for fixationof bone fragments which overcomes the problems associated with the knownart.

The means according to the invention has two basic functions; namely, abuttress function and a clamp function. Either function or both can beemployed dependent upon the particular embodiment selected to treat thefracture.

One example of the buttress function is to assist in the reduction of acompletely intra-articular fragment. Since this fragment is entirelywithin the joint, it is not possible to place a fixation device directlythrough it without compromising the articulating surfaces. One solutionfor stabilizing these types of fragments is to pack bone graft behindthe fragment, in order to force it up against the opposite side of thejoint. This requires bone from a bone bank, or removal of bone from adifferent site of the same patient. Both of these alternatives addadditional risk to the patient. A buttress pin according to theinvention provides a more stable means of buttressing such a fragment,without the risks of bone graft.

The basic design of the buttress pin is to provide a buttress on theintraosseous surface of a bone fragment to constrain it from moving in aparticular direction. In one embodiment, the buttress pin has a sectionwhich is passed through an opening in the cortex (either through thefracture or through drilled holes) and which can then be positioned tosupport an intra-articular fragment from the desired direction.

The clamp function is useful to stabilize a fragment when a transosseouspin or screw is not indicated. It combines an intraosseous andextraosseous buttress adjacent to a common bone cortex. In cases wherethere is no opposite stable cortex or in cases where any additionalholes in the fragment would cause further comminution, a small fragmentclamp could be used. A small fragment clamp according to the inventionallows a small fragment to be captured and secured to the cortex of boneadjacent to the fragment.

The basic design of the small fragment clamp is to provide a form forclamping a small fragment on its upper and lower surfaces which can thenbe secured to an adjacent portion of stable bone. In its preferredembodiments, the small fragment clamp is comprised of two main sections.One section is used to engage and buttress the fragment from theintraosseous surface of the cortical bone while the other section isused to engage the extraosseous surface. The sections are "pinched"together to grab the fragment securely and then are fastened to theadjacent cortex of stable bone.

In this way the small fragment clamp allows small fragments to begrasped, positioned, buttressed and secured in an anatomic position.Since the fragment is held in place by the gripping action of the"fingers" of the device, it is not applicable for fractures with largeforces across the fracture site, as in weight bearing joints. However,for fractures of the distal radius, it is ideal for assisting infixation that may be rigid enough to avoid the use of a cast.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in greater detailhereinbelow, with the aid of embodiments shown in the drawings. In theaccompanying drawings:

FIG. 1 shows one typical fragmentation for Colles' fractures;

FIGS. 2-4 are top, side and end views, respectively, of a firstembodiment of the invention;

FIG. 5 shows in sectional view application of the device of FIGS. 2-4 ona fracture;

FIGS. 6-8 are top, side and end views, respectively, of a secondembodiment of the invention;

FIGS. 9-11 are top, side and end views, respectively, of a thirdembodiment of the invention;

FIGS. 12-14 are top, side and end views, respectively, of a fourthembodiment of the invention;

FIGS. 15a-15f show application of the device of FIGS. 12-14 on afracture;

FIGS. 16-18 are top, side and end views, respectively, of a fifthembodiment of the invention;

FIGS. 19-20 show application of the device of FIGS. 16-18 on a fracture,FIG. 20 being a cross-section taken on line XX--XX in FIG. 19;

FIGS. 21-23 are top, side and end views, respectively, of a sixthembodiment of the invention;

FIGS. 24-26 are top, side and end views, respectively, of a seventhembodiment of the invention;

FIGS. 27-28 show application of the device of FIGS. 24-26 on a fracture,FIG. 28 being a cross-section taken on line XXVIII--XXVIII in FIG. 27;

FIG. 29 shows in sectional view application of a combined deviceaccording to the invention on a fracture;

FIG. 30 is a top view of a further embodiment of the invention;

FIGS. 31-32 show the application of the device of FIG. 30 on a fracture,FIG. 32 being a cross-section taken on line XXVII--XXVII in FIG. 31;

FIG. 33 shows the application of an optional plate; and

FIGS. 34-35 show different embodiments of the plate according to FIG. 33in sectional view.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In FIG. 1 a typical fragmentation of the distal radius 81 is shown. Inthis case three fragments 82, 85, 86 are formed. A dorsal ulnar fragment82, an intra-articular fragment 85 and a palmar lip fragment 86. Thisfragmentation pattern is used for descriptive purposes only, in order toexplain the invention.

For the fixation of the intra-articular fragment 85 a buttress accordingto the invention is used. In the embodiment shown in FIGS. 2 to 4 thereis only one major part, namely a first part 41 or buttress pin. Thedistal end of the first part 41 is formed as a buttress 49. In thisembodiment the first part 41 is U-shaped in top view, and is furnishedwith pointed projections 45 for engagement with bone cortex. Thebuttress pin is secured to the stable bone with a bone screw 44cooperating with a washer 46.

Buttressing of an intra-articular fragment 85 from the intraosseous sideis not limited to use in the distal radius. Other joints, such as theelbow, knee, and ankle, are suitable for this type of device.

FIG. 5 shows application of the buttress pin of FIGS. 2 to 4 on afracture. The buttress pin is driven up behind the fragment 85 to pushit against the adjacent cortex. In this position the device is securedto the stable bone 81 with the bone screw 44 cooperating with the washer46. The pointed projections 45 help to give a stable fixation. Thisdevice 41 is stiff enough to allow the fragment 85 to be maintained inposition against the opposite side of the joint. On the other hand, thedevice 41 is flexible enough to allow it to be removed after fracturehealing without significant disruption of bone. Thus, this device 41buttresses from the intraosseous side of the fragment. All existingbuttress plates place the buttress on the superficial surface of thebone.

It will be additionally noted that the device 41 provides anintraosseous buttress to the cortical fragment 82 as shown in FIG. 5.This provides a stable floor against which this cortical fragment mayabut, providing additional stability to this fragment. It is readilyapparent that the device is capable of being used as an intraosseousbuttress for either an intra-articular fragment, an unstable corticalfragment, or a combination of the two.

For the fixation of the dorsal ulnar fragment 82 a small fragment clampaccording to the invention is used. The basic design of the smallfragment clamp is to provide a form of sandwiching effect for fixationof the fragment 82. This effect combines an intraosseous buttress withan extraosseous buttress in order to further constrain movement of thefragment, without the need of invasively drilling through the fragment.The fragment clamp is made of two parts. The first part grabs thefragment 82 from the undersurface and the second part grips the uppersurface of the fragment 82.

In a first embodiment of the fragment clamp shown in FIGS. 6 to 8 thefirst part 1 has two cross tabs 6, 7. The distal one 7 acts as a fulcrumor axis of rotation of the first part 1 on the second part 2. Thisprevents the first part 1 from lifting up out of the second part 2.

Both the first part 1 and the second part 2 have pointed projections 5for engagement with bone cortex.

In this embodiment the first part 1 is linear in top view and is bent inside view, the forward bent section being intended to grip and buttresson the intraosseous side of the fragment 82. The second part 2 has ageneral U-shape with two legs 3. To secure the components to the stablebone 81, bone screws 4 are applied through holes in the tabs 6, 7.

This fixation also secures the components 1, 2 to each other. Since thefirst and second parts 1, 2 are not directly coupled, the surgeon mayslide the first part 1 distally or proximally depending upon the size ofthe fragment intended to be firxed. Once the device is applied, however,the two parts 1 and 2 no longer move relative to each other. Thepressure of the cross tabs 6, 7 on the second part 2 essentially joinsthe first and second parts 1, 2 together.

In a second embodiment of the fragment clamp shown in FIGS. 9 to 11 thefirst part 11 has a cross pin 17, acting as a fulcrum for rotation ofthe first part. As in the first embodiment the first part 11 is linearhaving a bent section in side view, and the second part 12 has a generalU-shape with two legs 13 in top view and is linear in side view.

Fixation for the second embodiment is accomplished with bone screws 14passing through a matching washer 16. The washer 16 locks the first andsecond parts 11, 12 to each other as well as to the bone 81.

Both the first and second parts 11, 12 have pointed projections 15 forengagement with bone cortex.

A third embodiment of the fragment clamp is shown in FIGS. 12 to 14. Inthis embodiment the first and second parts 21, 22 have the same generalshape as in the above embodiments. Furthermore they are furnished withpointed projections 25 for engagement with bone cortex.

The second part 22 has a cross pin 27 and a cross bar 26 bridging thelegs 23 of the second part 22. The cross bar 26 is furnished with anopening for receiving a bone screw 24 securing the device to the stablebone 81. The cross bar 26 is also used to capture an upwardly directedhook 28 on the first part 21. In this embodiment the device has beenlimited to two components.

FIGS. 15a to 15f show one way to secure the device according to thethird embodiment to a stable bone 81. The first part 21 is first placedby having it pass through the fracture 83. If necessary a notch 84 isremoved or a transosseous hole is made to allow the passage of the firstpart 21. When the first part has been placed with the pointed projection25 in engagement with and buttressing the intraosseous side of anunstable fragment 87, the second part 22 is placed on top of the firstpart 21 in a position where the hook 28 of the first part 21 is capturedby the cross bar 26. Finally a bone screw 24 passing through an openingin the cross bar 26 secures the device to the stable bone. As the screw24 is fastened the projections 25 of the first and second parts 21, 22will engage the bone cortex and stabilize the position of the device.Thus, the bone fragment 87 is sandwiched between the first and secondparts 21, 22 and is secured to the stable bone 81.

In some cases a hole is made in the stable bone at some distance fromthe actual fracture site. The first part is inserted through said hole.The rest of the device is secured as described above. Sometimes aspecial tap or clamping device is used to temporarily fix the first partto the stable bone. The unstable fragment is then placed on top of theintraosseous arms of the first part and the second part is thereafterplaced on top. Finally the tap is replaced with a screw and washer.

In FIGS. 16 to 18 a fourth embodiment of the fragment clamp according tothe invention is shown. This embodiment resembles the previousembodiments in having a first linear part 31 and a second U-shaped part32 with two legs 33. The first and second parts 31, 32 have projections35 for engagement with bone cortex.

In this embodiment there is no cross tab on the first part 31, insteadthe bone fragment itself prevents the first part 31 from lifting up outof the second part 32. The proximal end of the first part 31 has a hook38 which allows passage of a screw 34. The screw passes through a washer36. This design is cheap and simple to manufacture. Application of thisdevice on a bone is shown in FIGS. 19 and 20. FIG. 20 shows across-section taken along line XX--XX in FIG. 19.

As in the example shown in FIGS. 15a to 15f the first part 31 is firstpassed through the fracture 83, with or without a notch having beentaken out. When the first part 31 is positioned the second part 32 isplaced with the legs 33 of the second part 32 on both sides of the firstpart 31 and with the distal ends of the legs 33 on the upper side of thefragment 82. Then the washer 36 is placed bridging the legs 33 of thesecond part 32. The washer 36 has a hole for receiving a bone screw 34in alignment with the center of the hook 38 of the first part 31.Finally, the bone screw 34 secures the device on the stable bone 81whereby the distal ends of the first and second parts 31, 32 sandwichthe fragment 83. Thus, the first part 31 forms an intraosseous buttressand the second part 32 forms an extraosseous buttress.

FIG. 30 shows one further embodiment of the fragment clamp according tothe present invention. This embodiment has a first U-shaped part 91 withtwo legs 97 and a second U-shaped part 92 with two legs 93. Beforeplacing the first part 91, the legs 97 of said part 91 are bentdepending on the site of the fracture 83. Application of this device ona bone is shown in FIGS. 31 and 32. FIG. 32 shows a cross-section takenalong the line XXXII--XXXII in FIG. 31. When applying the fragmentclamp, the first part 91 is first passed through the fracture 83, withor without a the notch having been taken out. Then the second part 92 isplaced with the legs 93 of said part 92 on both sides of the first part91 and with the distal ends of the legs 93 on the upper side of thefragment 82. Both the first and second parts have pointed projections 95for engagement with bone cortex. A washer 96 is then placed bridging thelegs 93 of the second part 92. The washer 96 receives a bone screw 94,which secures the device on the stable bone 81. Thus, the distal ends ofthe first and second parts 91,92 sandwich the fragment 83. The firstpart 91 forms an intraosseous buttress and the second part 92 forms anextraosseous buttress.

Some embodiments of the small fragment clamp allow the first part to beplaced at a variable distance along the first component allowing central"fingers" extending as far as or farther than the outer fingers ifdesired or much shorter if desired. This feature allows the bend in thefirst part to be placed at the level of the fracture site where it wouldallow the first part to track up against the inner cortex of the bonefragment 82.

The above described embodiments are only examples of possible designsfor a device according to the invention. In other embodiments thedifferent parts of the embodiments shown are combined with differentparts of the other embodiments. Thus, in further embodiments, both thefirst and second parts have U-shape in top view, the lengths of the legsof the U-shape differ, the number of arms on the intraosseous and theextraosseous side vary etc. In one embodiment there are two armsintraosseous and one arm extraosseous.

In the embodiment shown in FIGS. 21 to 23 the small fragment clamp ismade in one piece. The clamp includes a base 62 and in side view a bentfirst part 61 for gripping and buttressing on the intraosseous side of abone fragment. For gripping and buttressing on the extraosseous side ofthe bone fragment the clamp is provided with two straight legs 63, whichare parallel with the first, bent part 61. Both the first part 61 andthe two legs 63 have pointed projections 65 for engagement with cortex.

To secure the clamp to the stable bone, bone screws 64 are appliedthrough holes in the base 62 of the clamp.

In FIGS. 24 to 26 a further embodiment according to the invention isshown, having both a clamping function and an intra-articular buttressfunction. The first part 71 has a general U-shape in top view with twolegs 77 connected with a loop 78. In side view the legs 77 of the firstpart 71 show an intra-articular buttress 79 connected to the end of abent section of the legs 77, which bent section cooperates with legs 73of the second part 72 to grip a bone fragment.

To secure the clamp and the intra-articular buttress to the stable bonea bone screw 74 is used. The screw 74 passes through a washer 76,bridging the legs 73 of the second part 72, and passes through the loop78 of the first part.

An example of application of the device of FIGS. 24 to 26 is shown inFIGS. 27 and 28. FIG. 28 shows a cross-section taken along the lineXXVIII--XXVIII in FIG. 27. The first part 71 is first passed through thefracture, with or without a notch having been taken out, or through ahole made in the stable bone. To position the first part 71 with theintra-articular buttress 79 and the legs 77 in the desired positions itmay be necessary to bend either part somewhat in one direction or other.When the first part 71 has been placed the unstable fragment 82 to begripped by the fragment clamp is placed on top of the legs 77 of thefirst part 71, which legs 77 function as a buttress for the fragment 82.Then the second part 72 and the washer 76 are placed. The washer 76bridges the legs 73 of the second part 72 and has an aperture forreceiving the bone screw 74 in alignment with the center of the loop 78of the first part 71. Finally, the bone screw 74 secures the device onthe stable bone 81 whereby the legs 73, 77 of the first and second partssandwich the dorsal ulnar fragment 82 at the same time as theintra-articular buttress 79 of the first part 71 buttresses anintra-articular fragment 85.

In FIG. 29 a further device is shown applied on a fracture, having botha clamping function and an intra-articular buttress function. In thisembodiment the first part 51 grips on the lower side of a first fragment82 at the same time as an intra-articular buttress 59 of the first part51 forces a second fragment 85 against the opposite side of the joint.The second part 52 grips on the upper side of the first fragment 82.This device is secured to the stable bone 81 with a bone screw 54passing through a washer 56. As in the previous embodiments pointedprojections are used to stabilize the device further.

In some embodiments there are no pointed projections and in otherembodiments there are one or more raised areas for contact with thebone. In a further embodiment (not shown) a two piece first part isused, which can be coupled during insertion at the site of bonepenetration.

The method of placement of the device according to the inventionsometimes require the removal of a small notch of bone to allow passageof the first part. The first part is flexible enough to allow itsremoval simply by sliding this member proximally at the time of deviceremoval.

In cases where the patient has a severe fragmentation and possibly softbone (osteoporosis), there is a risk that that the legs of the secondpart find a crack between the fragments and fall within the crack. Toavoid this risk a small plate 100 is placed between the extraosseoussurface of the fragments and the legs 93 of the second part 92. In thisway the load of the clamp is spread over a wider area. Although theplate 100 is shown in FIG. 33 in connection with the device according toFIG. 30, a person skilled in the art realizes that said plate could beused with any fragment clamp according to the invention.

In its most simple embodiment the plate 100 is a simple straight plate.In further embodiments the plate is furnished with means 103, 104 toconstrain the plate from migrating. Two examples of this are shown incross-section and enlarged in FIGS. 34 and 35. The plate 101 accordingto FIG. 34 has a raised area 103 between the legs 93 of the second partof the fragment clamp. The plate 102 according to FIG. 35 is furnishedwith two seats 104 for receiving the legs 93 of the upper part of thefragment clamp. In a further embodiment (not shown) the plate has twoslots at the distal edge to allow the legs 93 near the tip to passthrough to the bone. In still a further embodiment (not shown) two smallholes are placed near the distal edge of the plate to allow the pointedprojections of the outer component to gain some purchase on the plate.Thus, the plate is constrained from migrating by co-operation betweenthe legs 93 of the clamp and a constraining means 103, 104 of the plate101, 102. If needed, the plate 100, 101, 102 is bent to conform to thedorsal surface

As an option (not shown) the legs of both the first part and the secondpart are delivered straight i.e. not bent in side view. In this case thelegs of the first part are custom bent depending on the fracture site,the size of the fragments etc. before application by the surgeon. Inthis embodiment it is possible to cut the ends of the legs to desiredlengths and optionally bend in a point at the end if desired.

The first and second parts of this device are preferably made of wireshaving a diameter between 0.010" to 0.250". In one embodiment 0.045"wire is used and in a second embodiment 0.054" wire is used. In otherembodiments the first and second parts are not made of wires, in whichcase the crosssection of the legs of each part has the shape of a bar,plate, triangle, hexagonal or the like.

In one further embodiment (not shown) at least one of the legs of thefirst and/or second part is bent or angled in top view. The above bentor curved sections are predominantly arranged at the tip of the legs,but in some embodiments the entire legs (or leg) has a bent or angledshape as viewed from above.

The expressions lower, upper etc as used in the description are used forconvenience and only refers to the drawings specifically referred to,without any limitations to the actual design of the products.

The above detailed description has referred to but a limited number ofembodiments of the present invention, but it will be readily perceivedby a person skilled in the art that the present invention encompasses alarge number of embodiments without departing from the spirit and scopeof the appended claims.

What is claimed is:
 1. An implantable surgical buttressing means forfixation of one or more bone fragments to an adjacent stable bone, saidbuttressing means comprising a first part of U-shape including a Uportion and two legs extending from said U portion to bear along anextraosseous surface of a stable bone, a bone screw for securing saidfirst part against said stable bone, said legs having bends to passthrough a fracture space between adjacent bone fragments and respectivedistal ends shaped to bear against an intraosseous surface of at leastone said bone fragment and provide a buttressing action thereagainstwithout drilling into said at least one bone fragment.
 2. An implantablesurgical buttressing means as claimed in claim 1, wherein said legs ofsaid first part have sufficient flexibility for introducing said legsthrough said fracture space into a position to bear against theintraosseous surface of at least one bone fragment and for removaltherefrom after bone healing.
 3. An implantable surgical buttressingmeans as claimed in claim 2, further comprising a second part includingan engaging portion comprising a leg shaped to bear against anextraosseous surface of at least one said bone fragment and positionedfor sandwiching said at least one bone fragment between said first andsecond parts, at least one of said legs of said first and second partsbeing bendable by hand and being cut prior to implantation of saidbuttressing means whereafter the thus cut end is then bent.
 4. Animplantable surgical buttressing means as claimed in claim 1, furthercomprising a second part including an engaging portion shaped to bearagainst an extraosseous surface of at least one said bone fragment andpositioned for sandwiching said at least one bone fragment between saidfirst and second parts.
 5. An implantable surgical buttressing means asclaimed in claim 4, further comprising means for securing said first andsecond parts in respective positions to sandwich said at least one bonefragment therebetween including fastener means for attaching saidbuttressing means to said stable bone.
 6. An implantable surgicalbuttrossing means as claimed in claim 4, comprising projections on atleast one of said parts.
 7. An implantable surgical buttressing means asclaimed in claim 1, further comprising a second part including anengaging portion shaped to bear against an extraosseous surface of atleast one said bone fragment and positioned for sandwiching said atleast one bone fragment between said first and second parts, and meansfor securing said first and second parts together such that said firstpart is positionable independently of said second part prior toattachment thereof to said first part.
 8. An implantable surgicalbuttressing means as claimed in claim 1, wherein said first and secondparts include respective legs of differing length.
 9. An implantablesurgical buttressing means as claimed in claim 1, wherein said legs areinitially straight and bendable by hand to form said bends prior toimplantation as a function of the fracture site and the shape and siteof said at least one bone fragment.
 10. An implantable surgicalbuttressing means as claimed in claim 1, comprising a washer extendingcrosswise on said legs for receiving the bone screw to secure the firstpart against the stable bone.
 11. An implantable surgical clamp meansfor fixation of one or more bone fragments to an adjacent stable bone,said clamp means comprising a first part for bearing along anextraosseous surface of a stable bone, a bone screw for securing saidclamp means against said stable bone, a second part supported from saidfirst part, said first and second parts having distal ends spaced fromone another so that the distal ends of said parts can respectively bearagainst the extraosseous and intraosseous surfaces of at least one bonefragment to sandwich said at least one bone fragment between the distalends of the first and second parts, one of said parts being of U-shapeand including a U portion and two legs extending in spaced relation fromsaid U portion and means for securing said first and second partstogether.
 12. An implantable surgical clamp means as claimed in claim11, wherein the part which bears against the intraosseous surface ofsaid at least one bone fragment includes a buttressing portion whichbuttresses a second bone fragment concurrently while said at least onebone fragment is sandwiched between the distal ends of said first andsecond parts.
 13. An implantable surgical clamp means as claimed inclaim 11, wherein said first and second parts are of pin constructionhaving a diameter between 0.10 and 0.250".
 14. An implantable surgicalclamp means as claimed in claim 11, comprising a plate extendingcrosswise on said legs of said U-shaped part, said bone screw beingengageable in said plate for securing said U-shaped part to said stablebone.
 15. An implantable surgical clamp means as claimed in claim 14,wherein said first and second parts are slidably supported from oneanother, said means for securing said first and second parts togetherincluding attachment means to secure said first and second partstogether after said first and second parts have been slidably adjustedto engage said at least one bone fragment.
 16. An implantable surgicalclamp means as claimed in claim 14, wherein said first part is said Ushaped part.
 17. An implantable surgical clamp means as claimed in claim14, wherein said second part is said U shaped part.
 18. An implantablesurgical clamp means as claimed in claim 11, wherein said first andsecond parts are integrally formed.